Respirator

ABSTRACT

Embodiments of the present disclosure relate to a mask or shield adapted to generate a flow of positive pressure air directed through substantially opposing jets that creates a stream of laminar flow filtered air to create a turbulent air pocket therein for supplying filtered breathable air to a wearer&#39;s face.

RELATED APPLICATIONS

This application derives priority from New Zealand patent applicationnumbers 709617 and 713259 incorporated herein by reference.

TECHNICAL FIELD

Described herein are respirators. More specifically, a mask or shieldcomprising a flow of positive pressure air directed throughsubstantially opposing jets that creates a stream of laminar flowfiltered air to create a turbulent air pocket therein for supplyingfiltered breathing air to a wearer's face and to exclude outsideunpurified air. Also a mask or shield comprising a flow of positivepressure air directed via a powered impeller unit that is configured todistribute positively pressurised filtered breathable air inside theface mask in a substantially 360° plane or arc substantially parallel tothe internal surface of the face mask and to exclude external unpurifiedair. The mask is separated from and does not form a seal around awearer's face unless required such as in a deadly environment ormalfunction.

BACKGROUND ART

The air we breathe contains varying amounts of particles such as dust,dirt pollen, smog and noxious fumes. Air pollution is fast becoming oneof the largest health threats of the industrial world. Lung cancer andcardiovascular disease are increasing because of factory and vehicle airpollution where recent studies have shown lung cancer is two to threetimes more common in cities than in the countryside despite similarrates of tobacco smoking. Workers in certain industrial or agriculturaloperations are exposed to toxic dusts, mists and fumes which can causeillness or death even if inhaled in relatively small quantities over aperiod of time.

Many persons, because of their jobs, lifestyle or location, must exposethemselves to airborne particulate matter or fumes that are allergenic,or which can be injurious to their health. The size of the particles isa main determinant of where in the respiratory tract the particle willcome to rest when inhaled. Larger particles are generally filtered inthe nose and throat via cilia and mucus, but particulate matter smallerthan about 10 micrometres, referred to as PM₁₀, can settle in thebronchi and lungs and cause health problems. The 10 micrometre size doesnot represent a strict boundary between respirable and non-respirableparticles, but has been agreed upon for monitoring of airborneparticulate matter by most regulatory agencies. Because of their smallsize, particles in the order of ˜10 micrometres or less (PM₁₀) canpenetrate the deepest part of the lungs such as the bronchioles oralveoli.

Similarly, so-called fine PM, particles smaller than 2.5 micrometres,PM_(2.5), tend to penetrate into the gas exchange regions of the lung(alveolus), and very small particles (<100 nanometres) may pass throughthe lungs to affect other organs.

Some persons are allergic to certain pollens or dust occurring naturallyin the air and manifest this by an allergic reaction known as Hay Fever.Quite often, if uncontrolled, this allergic reaction progresses to aserious sinus condition or asthma. Also, the purity or quality of airmay be affected by the presence of infectious airbourne contaminates.

Face masks are used to combat air pollution and contaminates that affectthe quality of air. A conventional face mask is usually manufactured outof a piece of material that aims to filter out particulate material andseals or contacts against the face. One example is a mask that ismanufactured out of cotton material, with lots of leakage around theface and within the mask, the filter either being just a tiny squareinside the cotton mask or the entire mask itself. Nevertheless thesetypes of mask are not particularly effective at filtering outparticulate matter. Furthermore, these types of mask may only addressair particulates and not noxious gases. Also, as the mask contacts theface, this is uncomfortable for a wearer and some skin types aresensitive to conventional mask material and extended use can create skinirritation and even skin damage. Even users with non-sensitive skin maydevelop skin irritations from face mask contact.

A mask that contacts the face of a user with facial hair can not form aneffective seal due the facial hair forming a barrier between the maskand skin contact surface. In fact, a study on the effect of facial hairon the face seal of negative-pressure respirators has shown at least a330 fold drop in protection of a dust mask when used with a beard.Results such as this indicate that the presence of a beard greatlyincreases the leakage through the respirator face seal, and this leakageshould not be permitted when users are required to wear respirators.Furthermore, wearing a conventional mask makes communication difficultboth audibly and visually.

Style is also a consideration for a wearer and some prior art masks arebulky and those considered to be unaestheticaly pleasing to the eye areless likely to be worn.

Conventional respiratory filter masks are often worn by people who areexposed to airborne particulate matter or noxious gases or fumes toavoid inhaling these harmful substances. In order to achieve aneffective efficiency and an unencumbering resistance to airflow,conventional respiratory filter masks are cumbersome and of a designthat makes them impractical for everyday use. For example, wearing oneof these face mask filters is very uncomfortable with necessarilytight-fitting head straps and face mask seals. Notwithstanding that, allpeople's faces are different in shape making it difficult to achieve apositive seal with the prior art models. In addition, the wearer of oneof these masks must forcefully inhale against the pressure drop of theair passing through the filter media and when exhaling must force theair out through an exhaust valve. After a period of time this can becomeuncomfortable to normal people and exhausting to those with respiratoryproblems.

Full face coverage filter masks that do cover the eyes in addition tonose and mouth are often prone to fogging of the transparent face shieldand are even more uncomfortable to wear. As above, speech and sight aregreatly impaired and bulky hoses and filter cartridges are cumbersomeand unsightly to wear. In fact prior art face mask filter respiratorsare so cumbersome and uncomfortable that many people (including allergysuffers) risk the health hazards involved rather than wear this type ofprotection.

From the above, it can be seen that there is a need for an improved flowor face mask that overcomes disadvantages of known face masks or atleast provides the public with a useful choice.

Further aspects and advantages of the process and product will becomeapparent from the ensuing description that is given by way of exampleonly.

SUMMARY

Described herein are respirators. More specifically, a mask or shieldcomprising a flow of positive pressure air directed throughsubstantially opposing jets that creates a stream of laminar flowfiltered air to create a turbulent air pocket therein for supplyingfiltered breathing air to a wearer's face and to exclude outsideunpurified air. Also a mask or shield comprising a flow of positivepressure air directed via a powered impeller unit that is configured todistribute positively pressurised filtered breathable air inside theface mask in a substantially 360° plane or arc substantially parallel tothe internal surface of the face mask and to exclude external unpurifiedair. The mask is separated from and does not form a seal around awearer's face unless required such as in a deadly environment ormalfunction.

In a first aspect there is provided a respirator comprising:

-   -   a face shield with an attachment means for attaching the face        shield to a face region of a wearer;    -   at least two substantially opposing air supply lines in fluid        communication with each side of the face shield to provide a        positive stream of laminar flow of air; and    -   an air filter for filtration of the laminar flow of air;        wherein the at least two opposing air supply lines are spaced        apart and directed to allow streams of the laminar flow of        filtered air to collide at an intersection region within a        cavity of the face shield creating a turbulent flow of air that        radiates away from the intersection region therein for supplying        filtered breathing air to a wearer's face region and exclusion        of outside unpurified air, and wherein the face shield does not        form a seal around the face region of the wearer.

In a second aspect there is provided a respirator comprising:

-   -   a face mask configured to cover the face of a user; and    -   at least one air filter attached to the face mask and configured        to filter unpurified air to provide breathable air;        wherein    -   the respirator also comprises a powered impeller unit mounted on        the face mask and configured to compress and distribute the        breathable air inside the face mask in an arc substantially        parallel to the internal surface of the face mask; and    -   the face mask forms a gap between an edge of the face mask and        the user's face and configured to allow a positive flow of the        breathable air together with exhaled air to exit the face mask        and exclude ingress of external unpurified air.

In a third aspect there is provided a respirator comprising:

-   -   an air delivery system for generation of a positive flow of air;    -   a face mask configured to cover the face of a user; and    -   the face mask forms a gap between an edge of the face mask and        the user's face and configured to allow the positive flow of        breathable air together with exhaled air to exit the face mask        and exclude ingress of external unpurified air;        wherein    -   the gap between the edge of the face mask and the user's face        closes to form a seal when air pressure inside the mask drops to        a predetermined level.

Advantages of the above include a respirator with portable air deliverysystem or where the air delivery system is integrated into the mask forcompactness. The face shield is removable and manufactured out of a nonporous material so that the face shield is easily cleaned and does notabsorb gases or other types of pollutants. Also, no condensation formsas there is a positive flow of air and an engineered gap area for bleedair to the exterior or design spaces. In this way, the face mask ishygienic and once cleaned can be shared between different users. Thematerial of the face shield is dynamically flexible or rigidly solid,interchangeable and moulded to accommodate different sized faces or toaesthetically alter the look of the shield. A moulded interior surfaceof the face shield allows directional flow of air emanating from thecentre of the cavity of the face shield to radiate out therebypreventing a venturi effect entraining outside air, and provides acontrol of bleed air to the exterior or design spaces. Also, the mouldedinterior surface of the face mask allows directional flow of airemanating from the impeller unit to radiate out in a substantially 360°plane or arc substantially parallel to the internal surface of the facemask but not directly at the user's mouth and nose. In this way, apocket of purified air in front of the mouth and nose is provided whilstalso allowing for exhaled air to escape. An advantage of the interiormould surface is that it controls the direction of the bleed of air suchthat there is no high speed air blowing into eyes of the wearer. Ahollow section of the arm provides an attachment point for the integralair supply line to the face shield thereby minimising components of therespirator and hence reduced manufacturing costs and a more streamlinedaesthetic appearance. The arm is foldable to allow for ease of storagewhen the respirator is not in use. There is a mechanism for adjustmentfor both width and length of the arms that rest on top of the ear. Inthis way, the fitment of the face shield is easily accommodated to suitthe size and shape of a wearer's face. The attachment points utilise areleasable attachment means such as a user's eyewear. The attachmentmeans provides a conduit for electrical wiring from a power source, andthe attachment points provide the functionality of an electricalconnection between the power source and the powered impeller unit.Therefore, the attachment points support and centre the face mask on aface region of a user, wherein the face mask does not contact the faceregion nor form a seal around the face region of the user.

Advantages of a face mask or shield that does not require a seal arethat it does not contact the skin (no skin irritation and hence morecomfortable to wear), the face mask does not need to be monitored toensure a positive seal to keep out pollutants, and the wearer does nothave to forcefully inhale or exhale against the pressure drop associatedwith a sealed system.

Furthermore, wearers with facial hair can benefit from this face shieldunlike conventional masks where a positive seal is required. As above,an engineered cavity within the mask and gap area is advantageouslydimensioned to optimise supply air flow and bleed velocity such that apocket of purified air in front of the mouth and nose is created whilstalso allowing for exhaled air to escape. The design also controls thedirection of the bleed air so that there is no high speed air blowinginto the eyes. The minimal design of the components of the respiratorreduces manufacturing costs and provides a more streamlined aestheticappearance.

A further advantage is that the motor and the pressure sensor are veryclose to the mouth and nose. When the user takes a sharp inhalation ofbreath, the close proximity of the motor and the very small air columnenable the system to respond very quickly to maintain positive pressure,and ensure that the direction of the air flow is not reversed bybreathing in.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the respirator apparatus, operation and uses thereofwill become apparent from the following description that is given by wayof example only and with reference to the accompanying drawings inwhich:

Respirator with Rear Integrated Air Delivery System

FIG. 1 illustrates a front perspective view of one embodiment of arespirator with rear integrated air delivery system being worn by auser;

FIG. 2 illustrates a front schematic view of the same respirator of FIG.1;

FIG. 3 illustrates a side view of the same respirator of FIGS. 1 and 2;

FIG. 4 illustrates a rear schematic view of the respirator of FIGS. 1, 2and 3;

FIG. 5 illustrates a front schematic drawing of the air flow within thecavity of the face shield of the respirator showing laminar to turbulentflow; and

FIG. 6 illustrates a side schematic drawing of the air flow within acavity of the face shield of the respirator.

Respirator with Dual Integrated Air Delivery Systems

FIG. 7 illustrates a rendered side view of one preferred embodiment of arespirator with dual integrated air delivery system being worn by auser;

FIG. 8 illustrates a front schematic view of the same respirator of FIG.7;

FIG. 9 illustrates a further side view of the same respirator of FIGS. 7and 8;

FIG. 10 illustrates a rear schematic view of the respirator of FIGS. 7,8 and 9;

FIG. 11 illustrates a top schematic view of the respirator with dual airdelivery system with air tube and arms in the unfolded position;

FIG. 12 illustrates a top schematic view of the respirator of FIG. 11,but with the air tube and arms in the folded position.

Respirator with Separate Air Delivery System

FIG. 13 illustrates a rear perspective view of a further embodiment of arespirator with separate air delivery system being worn by a user;

FIG. 14 illustrates a front view of the same respirator of FIG. 13;

FIG. 15 illustrates a side profile view of the respirator of FIGS. 13and 14;

FIG. 16 illustrates a rear view of the same respirator of FIGS. 13 to15.

Respirator with Front Integrated Air Delivery System

FIG. 17 illustrates a side view of a further preferred embodiment of arespirator with front mounted impellor being worn by a user with fullframe safety glasses attached;

FIG. 18 illustrates a front view of the same respirator of FIG. 17;

FIG. 19 illustrates a front view of the same respirator of FIGS. 17 and18 with radial direction of air flow as indicated between mask and face;

FIG. 20 illustrates a side view of the same respirator of FIGS. 17 to 19with direction of air flow as indicated within a cavity;

FIG. 21 illustrates a front view of the same respirator of FIGS. 17 to20 with half-frame eyewear attached to the face mask;

FIG. 22 illustrates a side view of the same respirator of FIG. 21 withhalf-frame eyewear attached to the face mask;

FIG. 23 illustrates a side perspective schematic view of the samerespirator of FIGS. 17 to 20 with protective eyewear attached to theface mask; and

FIG. 24 illustrates the internal cavity of the face mask of therespirator of FIGS. 17 to 23.

Respirator with Floating Seal

FIG. 25 illustrates a side schematic view of another embodiment of arespirator with a floating seal in an open position; and

FIG. 26 illustrates a side schematic view of the respirator of FIG. 25with the floating seal in a closed position.

DETAILED DESCRIPTION

As noted above, described herein are respirators. More specifically, amask or shield comprising a flow of positive pressure air directedthrough substantially opposing jets that creates a stream of laminarflow filtered air to create a turbulent air pocket therein for supplyingfiltered breathing air to a wearer's face and to exclude outsideunpurified air. Also a mask or shield comprising a flow of positivepressure air directed via a powered impeller unit that is configured todistribute positively pressurised filtered breathable air inside theface mask in a substantially 360° plane or arc substantially parallel tothe internal surface of the face mask and to exclude external unpurifiedair. The mask is separated from and does not form a seal around awearer's face unless required such as in a deadly environment ormalfunction.

For the purposes of this specification, the term ‘about’ or‘approximately’ and grammatical variations thereof mean a quantity,level, degree, value, number, frequency, percentage, dimension, size,amount, weight or length that varies by as much as 30, 25, 20, 15, 10,9, 8, 7, 6, 5, 4, 3, 2, or 1% to a reference quantity, level, degree,value, number, frequency, percentage, dimension, size, amount, weight orlength.

The term ‘substantially’ or grammatical variations thereof refers to atleast about 50%, for example 75%, 85%, 95% or 98%.

The term ‘comprise’ and grammatical variations thereof shall have aninclusive meaning—i.e. that it will be taken to mean an inclusion of notonly the listed components it directly references, but also othernon-specified components or elements.

The term ‘respirator’ or grammatical variations thereof refers to apowered air-purifying respirator (PAPR). The purpose of a PAPR is totake air that is contaminated with one or more types of pollutants,remove a sufficient quantity of those pollutants and then supply the airto the user. A PAPR may comprise a powered fan which forces incoming airthrough one or more filters for delivery to the user for breathing. Thefan and filters may be carried by the user or the air may be fed to theuser via tubing while the fan and filters are remotely mounted.

The term ‘face shield’ or grammatical variations thereof refers to acomponent or device of the respirator used to protect a wearer's face(or part thereof) from external pollutants or particulates and directpurified air in front of the mouth and nose whilst also allowing forexhaled air to escape. Throughout the specification, the face mask orshield may also be referred to as an Air Focusing shield (AFS).

The term ‘powered impeller unit’ refers to a rotor and associated motorused to increase the pressure and flow of air from a filter into theinternal cavity of a face mask.

The term ‘positive stream of laminar flow of air’ or grammaticalvariations thereof refers to a positive pressure of air where the fluidor air flows in substantially parallel layers, with no disruptionbetween the layers. This is in contrast to turbulent flow which is aless orderly flow regime that is characterised by eddies or smallpackets of fluid particles which result in lateral mixing.

The term ‘positive flow’ or grammatical variations thereof refers to alaminar flow of air created by the powered impeller unit into theinternal cavity of the face mask and out of the gap between an edge ofthe face mask and the users face. This laminar flow of air provides aconstant supply of filtered breathable air for the user and excludeslateral mixing of unpurified external air in the face mask from the gap.This is in contrast to turbulent flow which is a less orderly flowregime that is characterised by eddies or small packets of fluidparticles which results in lateral air mixing.

The term ‘gap area’ or grammatical variations thereof refers to anengineered area between the skin surface and the face mask whenpositioned at a face region of a wearer. This may be calculated by theaverage gap distance of the mask edge from the skin surface multipliedby the mask edge perimeter. It should be understood by those skilled inthe art that the gap distance from the skin surface may vary due to anumber of factors, for example mask design and variation in contours ofa user's face.

The term ‘cavity’ or grammatical variations thereof refers to anengineered internal space between the skin surface and the face mask ata region where laminar flow of air is directed to intersect.

In a first aspect there is provided a respirator comprising:

-   -   a face shield with an attachment means for attaching the face        shield to a face region of a wearer;    -   at least two substantially opposing air supply lines in fluid        communication with each side of the face shield to provide a        positive stream of laminar flow of air; and    -   an air filter for filtration of the laminar flow of air;        wherein the at least two opposing air supply lines are spaced        apart and directed to allow streams of the laminar flow of        filtered air to collide at an intersection region within a        cavity of the face shield creating a turbulent flow of air that        radiates away from the intersection region therein for supplying        filtered breathing air to a wearer's face region and exclusion        of outside unpurified air, and wherein the face shield does not        form a seal around the face region of the wearer.

The face shield may be removable and manufactured out of a non porousmaterial. In this way, the face shield can be easily cleaned and may notabsorb gases or other types of pollutants. Also, the material of theface shield may be dynamically flexible or rigidly solid as required.This allows the face shield to be easily interchanged and moulded toaccommodate different sized faces and with the ability to aestheticallyalter the look of the shield. For example, a face shield manufacturedout of transparent material may allow a wearer to easily communicatewith others with both visual and vocal expression.

The face shield may include a moulded interior surface that allows aflow of air directed within the cavity of the face shield to radiate outto the peripheral edges of the face shield thereby preventing a venturieffect entraining outside air and provides a control of bleed air to theexterior. In this way, a pocket of purified air is provided in front ofthe mouth and nose whilst also allowing for exhaled air to escape.

The interior mould surface may control the direction of the bleed of airsuch that there is no high speed air blowing into eyes of the wearer.

The attachment means may include an arm member or temple that extendsover the ear to help hold the face shield in place.

The arm may include a separate or integrated earpiece that covers theportion of the arm that rests on top of the ear. The earpiece providesadded comfort to the wearer.

The arm or side member may be hollow to provide an integrated air supplyline to the face shield. In this way, the components of the respiratormay be minimised providing for reduced manufacturing costs and a moreaesthetic streamlined appearance.

The arm may be foldable to allow for ease of storage when the respiratoris not in use.

The face shield may include a mechanism for adjustment for both widthand length of the arms that rest on top of the ear. In this way, thefitment of the face shield can be easily adjusted to suit the size andshape of a wearer's face.

A further attachment means may include a nose piece that helps keep theface shield in a required position on the wearer's face region.

The above attachment means of two arms and a nose piece provide anattachment point to support and retain the face shield on a face regionof a wearer, wherein the face shield does not contact the face regionnor form a seal around the face region of the wearer. Advantages of aface shield that does not require a seal are that it does not contactthe skin (no skin irritation and hence more comfortable to wear), theface shield does not need to be monitored to ensure a positive seal tokeep out pollutants, and the wearer does not have to forcefully inhaleor exhale against the pressure drop associated with a sealed system.Also, the above attachment points do not require contact to hair or topof the head, for increased comfort.

The air supply line may be a flexible hose attached to a pump housingconfigured to extend up a back, head or under a chin of the wearer. Itshould be appreciated by those skilled in the art that any type offlexible air hose may conceivably be used with this invention. Forexample, this may include, but not be limited to, clear silicon airline.

The flexible airline may include a manifold, Y-piece adaptor or twincoupling air line three-way splitter to allow a dual air lineconfiguration for integration into each arm member or on either side ofthe wearer's head. In this way, a positive stream of laminar flow of airmay be provided on each side of the face shield.

In one embodiment, a first jet nozzle may be spaced at an engineereddistance apart from a corresponding second jet nozzle attached to distalends of air lines such that a positive stream of laminar flow isdirected to the intersection region within the cavity of the faceshield. In this way, the jet nozzles are dimensioned and positioned suchthat they may not venturi external air into the cavity, but any venturieffect that may occur only recirculates purified air within the cavity.Optionally, the positive stream of laminar flow may be regulated, inpart, by adjusting the area of the nozzle opening, to more or lessrestrict the air flow and thereby increase or decrease the positivepressure inside the face shield.

It is envisaged that the dynamic pressure or positive pressure withinthe engineered gap area of the face shield may range from 1-20 Pa. Theinventor has found that an optimum pressure may be 5 Pa as therespirator allows for a continuous supply of purified air in the gapspace and there is no requirement of a high positive pressure. However,this should not be seen as a limitation on the embodiments envisaged forthis invention. If the outside air becomes more hazardous to the wearerand/or this outside air becomes more turbulent or “windy”, then thepositive pressure of the filtered air within the gap space of the faceshield may be increased in order to prevent possible infiltration of theoutside air. Conversely, the pressure may be decreased depending onambient conditions.

The gap area may range from 10-100 cm², wherein the gap area may becalculated from a supply air flow and bleed velocity respectively.

The supply air flow from a pump may range from 1-9 L/s or 0.001-0.09m³/s. The inventor has found that an optimum air flow may be 2-3 or upto 7 L/s or 0.002-0.003 up to 0.007 m³/s. By way of example, anover-supply of air given heavy breathing may be considered to beapproximately 0.5 L/s. It should be appreciated by those skilled in theart that the air supply should always be above the peak inhalation, i.e.an oversupply such that the outflowing direction of the air gap is notreversed.

The respirator may also comprise at least one air pressure sensorattached to the mask and configured to monitor air pressure inside andoutside the mask to send an electrical signal to an impeller unit motorto vary the amount of power to the impeller rotor thereby controllingthe speed of the impeller rotor to maintain positive air pressure withinthe interior cavity of the face mask.

As above, the bleed velocity may be dependent on the area of the gapspace. For example, the bleed velocity correlating to a particular gapspace may be 0.5 m/s:100 cm², 1 m/s:50 cm^(2,) or 2 m/s:25 cm²respectively.

The respirator may include an air delivery system or fan supply unitcomprising an electric motor, filter assembly and impeller or fan tocreate an air pump. In this way, a positive pressure flow of air may bedelivered to the respirator. The air flow and positive pressure may beregulated, in part, by adjusting the fan speed.

The air delivery system may be attached to a wearer's pocket, mounted onthe back of a wearer's head or fastened to a belt or some otherconvenient place by fastener such as a dip. In some instances, anddepending on advancement in electronic technology, the air deliverysystem may be integrated into the face shield or other components of therespirator itself.

The air delivery system may include two or more air delivery systemsi.e. motor, fan and filter assemblies mounted on either side of awearer's head.

The fan supply unit may be powered by a battery or batteries. Thebattery may be rechargeable or replaceable and be of sufficient capacityto allow the respirator to operate for a desired period of time. Thebattery or batteries may be mounted to the air delivery system itself ormay be worn elsewhere on a body with power being sent via a cable orother such means.

The air delivery system may include a filter media or a filtrationsystem. The filtration system may include a breather shield forprotection against the elements such as rain.

The filter media may include a three stage filtration system ormechanism where particulate and gas phase removal may be effected by useof composite filters and combinations thereof for differentapplications. For example, filtration mechanisms may include, but not belimited to, adsorption, absorption, size exclusion, interception,inertial impactment, electrostatic attraction and diffusion (Van derWaals forces).

The discharged air from the fan supply unit may pass through the filtermedia and in doing so, any particulate matter, i.e. dust, pollen, etc.in the air may be retained on or in the filter media, at least down tothe particle size limitation of the filter media used. The filter mediaused generally may be that with maximum porosity and yet may retain asufficient percentage of the minimum size of the offending particles thewearer may want to avoid. In this way, the filter has the leastresistance to air flow and therefore may require the least fan and powerrequirements and thereby the least size and weight overall, hence thefilter media may be interchangeable and/or removable.

The filtration efficiency of the filter media or mechanism may at leastmeet applicable industry standards by those skilled in the art such asAshrae 52.2 (2012), Eurovent EN 779 (2012), ASTM F2100-11 and N95-98 forface masks. As is known in the industry, N stands for respirator filtersthat may be used when no oil is present in the contaminates and 95identifies that filter has been tested and certified by the Nationalinstitute for Occupational Safety and Health (NIOSH) to have a filterefficiency level of 95% or greater against particulate aerosols. It isenvisaged that the filtration efficiency of the filter media when testedagainst applicable N95-98 industry standards may be at least be N98having a filtration rate of 98% to greater than 99%.

A nanofibre filter may be utilised in the composite filter media. Theuse of nanofibre filter technology may achieve higher efficiency for aparticular filtration mechanism as stated above. The inventor has foundthat the use of nanofibre for most penetrating particle size (MPPS)particulate filtration and volatile organic compounds (VOCs) has theadvantage of high efficiency with a low airflow resistance. Withoutbeing bound by theory, the high porosity with small pore sizes and largefibre surface area means the fine particles are trapped whilst stillallowing air to pass. This has the effect of lower power requirementsfor the fan and extended filtration life.

It is envisaged that a functional nanofibre may be used that mayinclude, but not be seen as limited to, antimicrobial, antibacterial andantiviral additives such as nano silver or manuka extract.

The composite filter media may utilise a gas phase adsorption filter orother type of gas phase filtration before removal of odour and/ornoxious gases.

As known in the industry, gas phase adsorption is the process of usingan adsorption media to adsorb gases and odours in an air stream. In oneembodiment activated carbon or alumina or the like may be utilised forodour absorption and to remove or reduce the levels of gases and odours.As above, this may be used in conjunction with some other form of airfiltration system or air filter (for example, nanofibre filter) to keepthe carbon or other media from collecting particulates.

Gas phase adsorption may be utilised where a specific type of gas needsto be removed or reduced. It has been found that the thicker the filter,the longer the adsorptive media may be in contact with the gas.

Carbon and other adsorptive media may have alimited life and it has beenfound that they may only adsorb 33% to 50% of their weight before theylose their optimum efficiency and are replaced.

In a second aspect there is provided a respirator comprising:

-   -   a face mask configured to cover the face of a user; and    -   at least one air filter attached to the face mask and configured        to filter unpurified air to provide breathable air;        wherein    -   the respirator also comprises a powered impeller unit mounted on        the face mask and configured to compress and distribute the        breathable air inside the face mask in an arc substantially        parallel to the internal surface of the face mask; and    -   the face mask forms a gap between an edge of the face mask and        the user's face and configured to allow a positive flow of the        breathable air together with exhaled air to exit the face mask        and exclude ingress of external unpurified air.

The face mask may not form a seal around the face of the user. It may beattached to a user's eyewear and may not contact the face of the user.In this way, the face mask may not cause skin irritation and hence ismore comfortable to a user to wear, the face mask may not need to bemonitored to ensure a positive seal to keep out pollutants, and the usermay not have to forcefully inhale or exhale against the pressure dropassociated with a sealed system. Also, the above attachment points maynot require contact to hair or top of the head, for increased comfort.

The face mask may be a half face mask configured to substantially coverthe mouth and nose of the user. In other embodiments the face mask maybe integrated into a full face mask with integral eye protection for theuser.

The face mask may be manufactured out of a non porous material such asplastic, metal or carbon fibre. In this way, the face mask can be easilycleaned and may not absorb gases or other types of pollutants. Also, thematerial of the face mask may be dynamically flexible or rigidly solidas required. This allows the face mask to be easily interchanged andmoulded to accommodate different sized faces and with the ability toaesthetically alter the look of the shield. For example, a face maskmanufactured out of transparent material may improve visibility offacial expressions when users are communicating.

The face mask may include a moulded interior surface that allows a flowof air directed within the cavity of the face mask to radiate out to theperipheral edges of the face mask, thereby preventing alateral mixing ofexternal unpurified air into the interior of the face mask from the gapbetween the edge of the face mask and the user's face. In this way, apocket of purified air is provided in front of the mouth and nose whilstalso allowing for exhaled air to escape.

The face mask also comprises at least one adjustable gate configured toprovide a controlled bleed of air from the internal cavity of the facemask to the eye region of the user. The interior mould surface of theface mask may control the direction of the bleed of air such that thereis no high speed air blowing directly into eyes of the user. The bleedof purified air keeps the internal surface of the eyewear lenses fromfogging, prevents contaminants contacting the eyes of the user and coolsthe eyes.

The eyewear may provide a conduit for electrical wiring from a powersource, either by having wires embedded in the eyewear frame or bysupporting the wires with a mechanical attachment to the eyewear frame.

An impeller unit may be positioned substantially centrally on the facemask in relation to the mouth of the user. An impeller unit may comprisean electric motor and an impeller rotor to form an air pump to create apositive pressure flow of air into the internal cavity of the face maskand exiting through the gap between the face mask and the user's face.In this way, the air pressure inside the cavity of the face mask ishigher than the external air pressure and enables a continual flow ofpurified air without stopping or reversing back into the internal cavityof the face mask from the external atmosphere via the gap. The impellerunit may be unshrouded (not enclosed in a case) on an external side ofthe face mask, in order not to impede the drawing of external air. Thedrawn flow of air is purified by an associated purifying air filter. Animpeller rotor compresses and distributes the flow of purified airemanating from the purifying air filter in a substantially 360° plane orarc substantially parallel to the internal surface of the face mask tocurve the air around the user's mouth and nose to create a volume offiltered air in front of the user's mouth and nose which the user cansafely breathe.

The fan supply unit may be powered by a battery. The battery may berechargeable or replaceable and be of sufficient capacity to allow therespirator to operate for a desired period of time. In one embodimentthe battery may be a lightweight lithium ion battery. Optionally a lowbattery indicator such as at least one LED bulb may indicate when thebattery is low on power. The battery may be attached to the user via abattery attachment means such as a belt dip or neck dongle. The batterymay be electrically attached to the eyewear via a power cord.

In alternative embodiments, the impeller unit may be powered from anexternal power source such as a vehicle battery or mains socket (12 voltDC, 240 volt AC power source) via an adapter.

The respirator may also comprise at least one air pressure sensorattached to the face mask and configured to monitor air pressure insideand outside the face mask to send an electrical signal to the impellerunit motor to vary the amount of power to the impeller rotor therebycontrolling the speed of the impeller rotor to maintain positive airpressure within the interior cavity of the face mask.

It is envisaged that the dynamic pressure or positive pressure withinthe engineered gap of the face mask may range from 1-20 Pa. The inventorhas found that an optimum pressure may be 5 Pa as the respirator allowsfor a continuous supply of purified air in the gap space and there is norequirement of a high positive pressure. However, this should not beseen as a limitation on the embodiments envisaged for this invention. Ifthe external air becomes more hazardous to the user and/or this externalair becomes more turbulent or “windy”, then the positive pressure of thefiltered air within the gap space of the face mask may be increased inorder to prevent possible infiltration of the external air. Conversely,the pressure may be decreased depending on ambient conditions.

The gap may range from 15-100 cm², wherein the gap may be calculatedfrom a supply air flow and bleed velocity respectively.

The supply air flow from a pump may range from 1-20 L/s or 0.001-0.20m³/s. The inventor has found that an optimum air flow may be 2-3 or upto 7 L/s or 0.002-0.003 up to 0.007 m³/s. By way of example, anover-supply of air given heavy breathing may be considered to beapproximately 0.5 L/s.

As above, the bleed velocity may be dependent on the area of the gapspace. For example, the bleed velocity correlating to a particular gapspace may be 0.5 m/s:100 cm², 1 m/s:50 cm^(2,) or 2 m/s:25 cm²respectively.

In one embodiment, the respirator may comprise an external moisturebarrier filter for protection against the elements such as rain, andinternal purifying air filter to filter impurities from the compressedair distributed by the impeller unit. Different types of filters thatmay work by various filtration mechanisms may include, but not belimited to, adsorption, absorption, size exclusion, interception,inertial impact, electrostatic attraction and diffusion (Van der Waalsforces).

The discharged air from the fan supply unit may pass through the filtermedia and in doing so, any particulate matter, i.e. dust, pollen, etc.in the air may be retained on or in the filter media, at least down tothe particle size limitation of the filter media used. The filter mediaused generally may be that with maximum porosity and yet may retain asufficient percentage of the minimum size of the offending particles theuser may want to avoid. In this way, the filter has the least resistanceto air flow and therefore may require the least fan and powerrequirements and thereby the least size and weight overall, hence thefilter media may be interchangeable and/or removable.

The filtration efficiency of the purifying air filter may at least meetapplicable industry standards by those skilled in the art such as Ashrae52.2 (2012), Eurovent EN 779 (2012). ASTM F2100-11 and N95-98 for facemasks. As is known in the industry, N stands for respirator filters thatmay be used when no oil is present in the contaminates and 95 identifiesthat filter has been tested and certified by the National Institute forOccupational Safety and Health (NIOSH) to have a filter efficiency levelof 95% or greater against particulate aerosols. It is envisaged that thefiltration efficiency of the filter media when tested against applicableN95-98 industry standards may be at least be N98 having a filtrationrate of 98% to greater than 99%.

A nano-fibre filter may be utilised in the composite filter media. Theuse of nano-fibre filter technology may achieve higher efficiency for aparticular filtration mechanism as stated above.

The inventor has found that the use of nano-fibre for most penetratingparticle size (MPPS) particulate filtration and volatile organiccompounds (VOCs) has the advantage of high efficiency with a low airflowresistance. Without being bound by theory, the high porosity with smallpore sizes and large fibre surface area means the fine particles aretrapped whilst still allowing air to pass. This has the effect of lowerpower requirements for the fan and extended filtration life.

It is envisaged that a functional nano-fibre may be used that mayinclude, but not be seen as limited to, antimicrobial, antibacterial andantiviral additives such as nano silver or manuka extract.

The composite filter media may utilise a gas phase adsorption filter orother type of gas phase filtration before removal of odour and/ornoxious gases.

As known in the industry, gas phase adsorption is the process of usingan adsorption media to adsorb gases and odours in an air stream. In oneembodiment activated carbon or alumina or the like may be utilised forodour absorption and to remove or reduce the levels of gases and odours.As above, this may be used in conjunction with some other form of airfiltration system or air filter (for example, nano-fibre filter) to keepthe carbon or other media from collecting particulates.

Gas phase adsorption may be utilised where a specific type of gas needsto be removed or reduced. It has been found that the thicker the filterthe longer the adsorptive media may be in contact with the gas.

Carbon and other adsorptive media may have a limited life and it hasbeen found that they may only adsorb 33% to 50% of their weight beforethey lose their optimum efficiency and are replaced.

The face mask also may comprise at least one releasable attachment meansfor a user's eyewear. In one embodiment the releasable attachment meansmay be at least one magnet positioned on the face mask and if required acorresponding magnetic strip on the eyewear, a helmet or the likeconfigured to provide a snap fit of the user's eyewear or helmet to theface mask. The magnet also may provide the functionality of anelectrical connection between a battery and the powered impeller unit.

The magnets may be embedded during manufacture of the face mask or bemodified after production to have magnets mechanically affixed.

In one embodiment, the at least one releasable attachment may be tworeleasable attachments positioned on a top edge of the face maskproximal the user's eyes and configured to attach to a lower edge ofeach lens of the eyewear. In this way, the eyewear is stabilised on theface mask. The eyewear can be detached and reattached to the respiratorquickly in seconds if required without reattaching the respirator oradjusting its fit once head mounted.

A further releasable attachment means may include a nose piece thathelps keep the face mask centred in the required position on the user'sface region.

The eyewear may either be safety glasses, corrective lens glasses orhalf lens frames.

The respirator may also be upgraded with other wearable technologiessuch as air contaminant sensors, wireless audio headphones, microphonesand/or an optical head up display or the like.

In a third aspect there is provided a respirator comprising:

-   -   an air delivery system for generation of a positive flow of air;    -   a face mask configured to cover the face of a user; and    -   the face mask forms a gap between an edge of the face mask and        the user's face and configured to allow the positive flow of        breathable air together with exhaled air to exit the face mask        and exclude ingress of external unpurified air;        wherein        the gap between the edge of the face mask and the user's face        closes to form a seal when air pressure inside the mask drops to        a predetermined level.

The above describes a floating seal configuration which may be useful ina noxious gas or other such deadly environments.

The gap between the edge of the face mask and the user's face may closeand form a seal when activated by a mechanical and/or electricalmalfunction or the like. For example, such as a battery fault, or fanfailure.

The seal may comprise a strip of flexible material on at least one edgeof the mask or shield that may be held away from the face by positiveair pressure or mechanical means. The elasticity of the material ormechanical means may pull the mask towards the face to form the sealwhen air pressure inside the mask drops below a predetermined level.

Advantages of the above include:

-   -   A compact, self-contained and portable respirator with portable        air delivery system having a battery power source which provides        breathable purified air to the user;    -   An easily detachable or removable face mask or shield        manufactured out of a non porous material so that the face        shield is easily cleaned and does not absorb gases or other        types of pollutants;    -   A face shield manufactured out of dynamically flexible or        rigidly solid material that is interchangeable and moulded to        accommodate different sized faces or to aesthetically alter the        look of the shield;    -   A moulded interior surface of the face shield allows a flow of        air directed within the cavity of the face shield to radiate out        thereby preventing a venturi effect entraining outside air and        provides a control of bleed air to the exterior or design        spaces. In this way, a pocket of purified air is created in        front of the mouth and nose whilst also allowing for exhaled air        to escape. An advantage of the interior mould surface is that it        controls the direction of the bleed air such that there is no        high speed air blowing into the eyes of the wearer;    -   An integrated powered impeller unit which is mounted on the face        mask and configured to compress and distribute filtered        breathable air inside the face mask at a higher pressure than        the external air and in a substantially 360° plane or arc        substantially parallel to the internal surface of the face mask        to create a pocket of purified air is created in front of the        mouth and nose;    -   A gap between the edge of the face mask and the users face        allows exhaled air to escape and together with the powered        impeller unit provides a positive flow of air through the face        mask which prevents lateral ingress of unpurified external air        from entering the gap;    -   A moulded interior surface of the face mask which together with        the impeller unit allows a flow of air directed within the        cavity of the face mask to radiate out thereby preventing        alateral inflow of unpurified air into the interior of the face        mask and providing a control of bleed air to the exterior eye        region. An advantage of the interior mould surface is that it        controls the direction of the bleed air such that there is no        high speed air blowing into the eyes of the user;    -   An arm or side member with a hollow section provides an        attachment point for the integral air supply line to the face        shield thereby minimising components of the respirator and hence        reduced manufacturing costs and a more streamlined aesthetic        appearance;    -   A foldable arm to allow for ease of storage when the respirator        is not in use;    -   A mechanism for adjustment for both width and length of the arms        that rest on top of the ear. In this way, the fitment of the        face shield is easily accommodated to suit the size and shape of        a wearer's face;    -   A face mask does not contact the face region nor form a seal        around the face region of the user which provides the advantage        of improved user comfort (no skin irritation and hence more        comfortable to wear), the face mask does not need to be        monitored to ensure a positive seal to keep out pollutants        (hence also effective for users with facial hair), and the user        does not have to forcefully inhale or exhale against the        pressure drop associated with a sealed system;    -   Releasable attachment points on a user's eyewear that support        and retain the face mask on a face region of a user which        provides the advantage of improved ease of use in removing the        face mask if needed and repositioning on a user's face without        the need to adjust head straps;    -   An engineered cavity within the mask and gap area is        advantageously dimensioned to optimise supply air flow, bleed        velocity such that a pocket of purified air in front of the        mouth and nose is created whilst also allowing for exhaled air        to escape;    -   A minimal design which reduces manufacturing costs and provides        a more streamlined aesthetic appearance;    -   A motor and pressure sensor that are very close to the mouth and        nose. An advantage of this is that when the user takes a sharp        inhalation of breath, the close proximity of the motor and the        very small air column enable the system to respond very quickly        to maintain positive pressure, and ensure that the direction of        the air flow is not reversed by breathing in; and    -   A safety feature that includes a floating seal for use in deadly        environments or mechanical/electrical malfunction.

The embodiments described above may also be said broadly to consist inthe parts, elements and features referred to or indicated in thespecification of the application, individually or collectively, and anyor all combinations of any two or more said parts, elements or features.

Further, where specific integers are mentioned herein which have knownequivalents in the art to which the embodiments relates, such knownequivalents are deemed to be incorporated herein as if individually setforth.

WORKING EXAMPLES

The above described respirator apparatus, operation and uses thereof arenow described by reference to specific examples.

Example 1—Respirator with Rear Integrated Air Delivery System

With reference to FIGS. 1, 2 and 3, a perspective, front and side viewof a respirator apparatus 1 respectively is shown that includes adetachable face shield 2 manufactured out of a moulded non porousmaterial. The face shield 2 includes a moulded interior surface thatallows a flow of air directed within a cavity 3 (best seen in FIG. 5) ofthe face shield 2 to radiate out thereby preventing a venturi effectentraining outside air and provides a controlled bleed of the air to theexterior. An arm member or ear hook 4 extends over the ear to help holdthe face shield 2 in place and is foldable to allow for ease of storagewhen the respirator 1 is not in use. Also, the arm member 4 is attachedto an integrated air supply line 5 to the face shield 2. A nose piece 6keeps the face shield 2 in a required position on the wearer's faceregion. In particular, the two arm members 4 and nose piece 6 ensurethat the face shield 2 does not contact the face region nor form a sealaround the face region of the wearer.

As shown, the face shield 2 includes an eye air deflector 7 fordeflecting air away from a wearer's eyes.

The air supply line 5 that is in fluid communication with the faceshield 2 is a clear hollow plastic material and configured to allow foran integrated dual air line 5 configuration on either side of thewearer's head such that a positive stream of laminar flow of air isprovided on each side of the face shield 2. In one embodiment, a jetnozzle (not shown) is attached to a distal end of the air supply line 5such that the positive stream of laminar flow is directed to theintersection region 8 (best seen in FIG. 5) within the cavity 3 of theface shield 2. The gap area (not shown) ranges from 10-100 cm², and iscalculated from the supply air flow and bleed velocity respectively (seecalculations further below).

The respirator 1 includes an air delivery system or fan supply unitcomprising an electric motor and an impellor or fan 16 to create an airpump, all housed within a pump housing. The air delivery system isintegrally attached to the air supply line 5 which is located about therear neck region of a wearer. The air delivery system is powered by arechargeable battery 9 housed within or located about the air deliverysystem and is of sufficient capacity to allow the respirator 1 tooperate for a continuous period of six hours or more.

The air delivery system or fan supply unit includes a filter media or afiltration system comprising a filter housing 10, rain deflector 11,nanofilter 12 and an activated carbon gas phase adsorption filter (notshown) for removal of particulates, odour and/or noxious gasesrespectively, again all contained within the air delivery system.

The respirator 1 is configured to operate as follows:

A positive pressure flow of air is generated by the air delivery systemto the respirator 1 and the air flow and positive pressure is regulated,in part, by adjusting the fan 16 speed. The discharged air from the airdelivery system passes through the composite filter media and in doingso, any particulate matter, i.e. dust, pollen, etc. in the air isretained on or in the filter media, at least down to the particle sizelimitation of the filter media used.

The fan 16 is regulated so that the discharged air from the filter mediaflows through the air supply line 5 at 5 L/s or 0.005 m³/s. Thedischarged purified air travels through the dual air feed supply line 5on either side of the wearer's head such that a positive stream oflaminar flow of air is provided on each side of the face shield 2.

With reference to FIG. 5, the two streams of laminar flow of filteredair 13 collide at an intersection region 8 within a cavity 3 of the faceshield 2 to create a turbulent flow of air 14 or diffuse pocket of airthat radiates away from the intersection region 8 therein. This createsan over-pressure of clean filtered air around the mouth and nose. Theoverpressure air then flows towards and out of the gap area (bleed air)along with exhaled air between the shield and face. The combination ofbleed air and exhaled air both prevent ingress of polluted air. Theinterior mould surface of the face shield 2 controls the direction ofthe bleed of air such that there is no high speed air blowing into eyesof the wearer. It is envisaged that the dynamic pressure or positivepressure within the engineered gap area of the face shield is 5 Pa asthe respirator 1 allows for a continuous supply of purified air in thecavity and gap area and there is no requirement of a high positivepressure. However, if the outside air becomes more hazardous to thewearer and/or this outside air becomes more turbulent or “windy”, thenthe positive pressure of the filtered air within the cavity and gap areaof the face shield is increased in order to prevent possibleinfiltration of the outside air. Conversely, the pressure is decreaseddepending on ambient conditions. The above change in pressure isregulated by a pressure sensor 15 mounted within the face shield 2.

As above, the bleed air velocity is dependent on the gap area. Forexample, the bleed velocity is 0.5 m/s, 1 m/s, or 2 m/s for a given gapspace of 100 cm², 50 cm², or 25 cm² respectively (see calculationsbelow).

Example 2—Respirator with Dual Integrated Air Delivery System

With reference to FIGS. 7, 8 to 10, a rendered side, front, side andrear view of a respirator apparatus 1 respectively is shown thatincludes a detachable face shield 2 manufactured out of a moulded nonporous material. The face shield 2 includes a moulded interior surfacethat allows a flow of air directed within a cavity 3 (best seen in FIG.5) of the face shield 2 to radiate out thereby preventing a venturieffect entraining outside air and provides a controlled bleed of the airto the exterior. An arm member or ear hook 4 extends over the ear tohelp hold the face shield 2 in place and is foldable via a hinge 17 toallow for ease of storage when the respirator 1 is not in use (bet seenin FIGS. 11 and 12). Also, the arm member 4 is attached to an integratedair supply line 5 to the face shield 2. A nose piece (not shown) keepsthe face shield 2 in a required position on the wearer's face region. Inparticular, the two arm members 4 and nose piece ensure that the faceshield 2 does not contact the face region nor form a seal around theface region of the wearer.

As shown, the face shield 2 includes an eye air deflector 7 fordeflecting air away from a wearer's eyes.

The air supply line 5 that is in fluid communication with the faceshield 2 is a clear hollow plastic material and configured to allow foran integrated dual air line configuration on either side of the wearer'shead such that a positive stream of laminar flow of air 13 is providedon each side of the face shield 2. In one embodiment, a jet nozzle (notshown) is attached to a distal end of the air supply line 5 such thatthe positive stream of laminar flow 13 is directed to the intersectionregion 8 (best seen in FIG. 5) within the cavity 3 of the face shield 2.The gap area (not shown) ranges from 10-100 cm², and is calculated fromthe supply air flow and bleed velocity respectively (see calculationsfurther below).

The respirator 1 includes dual air delivery systems or fan supply unitseach comprising an electric motor and an impellor or fan 16 to create anair pump, all housed within a pump housing. The dual air deliverysystems are integrally attached to the air supply line 5 which arelocated about each side below the ears of a wear's head. Each airdelivery system is powered by a rechargeable battery 9 located about theair delivery system and is of sufficient capacity to allow therespirator 1 to operate for a continuous period of six hours or more.

Each air delivery system or fan supply unit includes a filter media or afiltration system comprising a filter housing 10, rain deflector 11,nanofilter 12 and an activated carbon gas phase adsorption filter (notshown) for removal of particulates, odour and/or noxious gasesrespectively, again all contained within the air delivery system.

The respirator 1 is configured to operate as previously described abovefor Example 1 and need not be described again.

Example 3—Respirator with Separate Air Delivery System

With reference to FIGS. 13, 14 to 16, a perspective, front and side andrear view of a respirator apparatus 1 respectively is shown thatincludes a detachable face shield 2 manufactured out of a moulded nonporous material. The face shield 2 includes a moulded interior surfacethat allows a flow of air directed within a cavity 3 (best seen in FIG.5) of the face shield 2 to radiate out thereby preventing a venturieffect entraining outside air and provides a controlled bleed of the airto the exterior. An arm member or ear hook 4 extends over the ear tohelp hold the face shield 2 in place and is foldable to allow for easeof storage when the respirator 1 is not in use. Also, the arm member 4is attached to a hollow plastic side member 19 that provides anintegrated air supply line 5 to the face shield 2. A nose piece (notshown) keeps the face shield 2 in a required position on the wearer'sface region. In particular, the two arm members 4 and nose piece ensurethat the face shield 2 does not contact the face region nor form a sealaround the face region of the wearer.

As shown, the face shield 2 includes an eye air deflector 7 fordeflecting air away from a wear's eyes.

The air supply line 5 that is in fluid communication with the hollowside members 19 is a clear flexible silicon hose attached to an airdelivery system or fan supply unit configured to extend up to a manifold18. The manifold 18 allows a dual air line configuration for integrationinto each side member 19 on either side of the wearer's head such that apositive stream of laminar flow of air 13 is provided on each side ofthe face shield 2. In one embodiment, a jet nozzle (not shown) isattached to a distal end of each side member 19 such that the positivestream of laminar flow 13 is directed to the intersection region 8 (bestseen in FIG. 5) within the cavity 3 of the face shield 2. The gap area(not shown) ranges from 10-100 cm², and is calculated from the supplyair flow and bleed velocity respectively (see calculations furtherbelow).

The respirator 1 includes an air delivery system or fan supply unitcomprising an electric motor and a fan 16 to create an air pump, allhoused within the pump housing. The fan supply unit or air deliverysystem is attached to a wearer's pocket or fastened to a belt or someother convenient place by fastener such as a clip (not shown). The airdelivery system is powered by a rechargeable battery 9 housed within theair delivery system and is of sufficient capacity to allow therespirator 1 to operate for a continuous period of six hours or more.

The air delivery system or fan supply unit includes a filter media or afiltration system comprising a filter housing 10, nanofilter 12 and anactivated carbon gas phase adsorption filter (not shown) for removal ofparticulates, odour and/or noxious gases respectively, again allcontained within the air delivery system.

The respirator 1 is configured to operate as previously described forExamples 2 and 3 above, and need not be described again.

Example 4—Respirator with Front Integrated Air Delivery System

With reference to FIGS. 17 and 18, a respirator 1 for a user is shownthat includes a detachable protective eyewear 20 and a face mask 2manufactured out of a moulded non porous material. The face mask 2includes a moulded interior surface that allows a flow of air directedwithin a cavity 3 (best seen in FIG. 24) of the face mask 2 to radiateout to the outer edges of the face mask 2 thereby preventing an in-flowof external air into the interior of the face mask 2 and providing acontrolled bleed of the air to the exterior. The face mask also includesat least one adjustable gate 21 configured to allow the user to controlthe bleed of air from the internal cavity 3 of the face mask to theeyewear 20.

Attachment points 22 enable a magnetic snap fit to the eyewear 20 in theform of full face glasses (such as safety and/or prescription glasses)20 to ensure that the face mask 2 is positioned over a user's mouth andnose but does not contact the face region nor form a seal around theface region of the user.

The air supply to the respirator 1 is filtered by means of an externalmoisture filter 23 to prevent ingress of water from rain or the likeinto the cavity 3 of the face mask 2. An internal nanofilter 12 in theform of a N98 filter, filters the dry air from the moisture filter 23 toprovide purified breathable air by removal of odour and/or noxious gasparticles.

The respirator 1 includes a powered impeller unit 16 mounted on the facemask 2 and comprising an impeller motor and rotor (not shown) tocompress the in-flowing air and distribute it in a 360° plane or arcparallel to the internal surface of the face mask 2.

A gap 24 allows positive flow of purified air and of exhaled air butprevents lateral mixing of external unpurified air by ingress throughthe gap 24 into the cavity 3. The gap 24 area ranges from 15-100 cm²,and is calculated from the supply air flow and bleed velocityrespectively (see calculations further below).

The impeller unit 16 is powered by a power supply in the form of alightweight lithium ion battery 9 on board. The battery 9 may be varioussizes and capacities depending on the needs of the user. For example,the battery 9 may have sufficient capacity to allow the respirator 1 tooperate for up to two hours which may be useful in a situation where therespirator 1 is being used for short periods of time and a more compactbattery 9 is preferred. Alternatively a larger battery 25 or externalpower source 28 may be utilised to enable continuous operation for aperiod of six hours or more.

The battery 25 is electrically connected to the impeller unit 16 via apower cord 26. The rotor of the impeller unit 16 is adjustable by acontrol indicated in the region on the face mask by label 27.

An external and internal air pressure sensor 15 is configured to monitorthe air pressure outside and inside the face mask 2 and sends anelectrical signal to the impeller unit 16 thereby controlling the speedof the impeller rotor (not shown).

In use and with reference to FIGS. 19 and 20, the respirator 1 isconfigured to operate as follows:

A positive pressure flow of air is generated by the impeller unit 16 ofthe respirator 1 compressing and distributing filtered air from thenanofilter 12. The air flow and positive pressure is regulated, in part,by adjusting the impeller 16 rotor speed. By passing the discharged airfrom the impeller unit 16 through the nanofilter 12, any particulatematter, i.e. dust, pollen, etc. in the air is retained on or in thefilter media, at least down to the particle size limitation of thefilter media used.

The impeller unit 16 is regulated so that the discharged air flows at 5L/s or 0.005 m³/s.

This creates an overpressure of clean filtered air around the mouth andnose. The overpressure air, or bleed air, then flows towards and out ofthe gap 24 along with exhaled air between the shield and face. Thecombination of bleed air and exhaled air both prevent ingress ofpolluted air. The interior surface of the face mask 2 controls thedirection of the bleed of air such that there is no high speed airblowing into eyes of the user. It is envisaged that the dynamic pressureor positive pressure within the engineered gap of the face mask is 5 Paas the respirator 1 allows for a continuous supply of purified air inthe cavity 3 and gap 24. However, if the external air becomes morehazardous to the user and/or this external air becomes more turbulent or“windy”, then the positive pressure of the filtered air within thecavity and gap of the face mask is increased in order to preventpossible infiltration of the external air. Conversely, the pressure isdecreased depending on ambient conditions.

As above, the bleed air velocity is dependent on the gap 24. Forexample, for an airflow of 5 L/s the bleed velocity is 0.5 m/s, 1 m/s,or 2 m/s for a given gap space of 100 cm², 50 cm², or 25 cm²respectively (see calculations below).

With reference to FIGS. 21 and 22, the user's eyewear 20 in analternative embodiment may be half frame glasses 20.

With reference to FIG. 23, the magnetic attachment points 22 aid instabilising and positioning the face mask 2 in relation to the eyewear20.

With reference to FIG. 24, the impeller unit 16 is shrouded on theinternal cavity side of the face mask 2 by the nano-fibre filter 12. Amouth guard 29 prevents contact of the filter 12 and impeller unit 16with the user's mouth.

Example 5—Respirator with a Floating Seal

With reference to FIG. 25, a respirator 1 is shown where the face maskcomprising flexible 30 and rigid 31 material portions forms a gapbetween an edge of the face mask 2 and the user's face under positiveair pressure. This configuration is referred to as a floating seal thatcomprises a strip of flexible material 30 on at least one edge of themask or shield 2.

As noted above, the floating seal is held away from the face by positiveair pressure. The elasticity of the material 30 pulls the mask towardsthe face to form the seal i.e. the gap closes when the air pressureinside the mask drops below a predetermined level as shown in FIG. 26.

A floating seal configuration is used for the above describedrespirators 1 in a noxious gas or other such deadly environments. Also,the gap is closed or triggered when activated by a mechanical and/orelectrical malfunction or the like.

Exemplary Calculation

The following calculations may be used to determine the relationshipbetween bleed velocity, pressure and through area (gap space).

p=Density air 1.2 kg/m

P(Dynamic pressure)=p×V ²(velocity)m/s

Q(airflow)=V×A where Q is in m³/s, V is m/s and A is m²

Air is continually being refreshed in the cavity or pocket, hence thereis no requirement for a high positive pressure. Optimally, there is 5 Papressure (P) In the cavity or pocket.

The gap space (through area A) is calculated using a bleed velocity (V)of 0.5 m/s and a supply airflow (Q) of 5 L/s or 0.005 m³/s

Therefore, the through area is calculated as follows:

0.005/0.5=0.01 m² or 100 cm²

Therefore, it correlates that if the bleed velocity is doubled, then thethrough area is halved i.e. for 1 m/s bleed velocity, through area(gap)=50 cm².

The bleed velocity required to achieve a given pressure in the cavity orpocket is calculated as follows: V²=P/p. For the optimal pressure of 5Pa, V²=5/1.2 so V=2 m/s.

Therefore, it correlates that if the bleed velocity is halved, then thepressure decreases by a factor of 4 i.e. for 1 m/s bleed velocity,pressure=1.2 Pa.

-   -   Bleed velocity of 0.5 m/s for gap of 100 cm² (P=0.3 Pa)—maximum        gap space for effective operation;    -   Bleed velocity of 1 m/s for gap of 50 cm² (P=1.2 Pa); and    -   Bleed velocity of 2 m/s for gap of 25 cm² (P=4.8 Pa)—optimal        conditions.

Aspects of the present have been described by way of example only and itshould be appreciated that modifications and additions may be madethereto without departing from the scope of the invention as claimedherein.

What is claimed is:
 1. A respirator comprising: a face mask configuredto cover the face of a wearer and form an engineered gap between an edgeof the face mask and the face of the wearer when the face mask is worn;at least one air filter attached to the face mask and configured tofilter unpurified air to provide breathable air; a powered impeller unitmounted on the face mask, the impeller unit being oriented to emit thebreathable air inside the face mask in a substantially 360 degree plane;and a releasable attachment point on the face mask adapted forreleasably coupling the face mask to the face of the wearer via eyewearor head gear worn by the wearer, wherein the engineered gap isconfigured to allow a positive flow of the breathable air together withexhaled air to exit the face mask and exclude ingress of externalunpurified air.
 2. The respirator of claim 1, wherein the releasableattachment point comprises at least one magnet positioned on the facemask.
 3. The respirator of claim 2, wherein the at least one magnet isconfigured to provide a snap fit between the face mask and acorresponding magnetic strip on the eyewear or head gear to secure theface mask to the face of the wearer.
 4. The respirator of claim 2,wherein the magnet provides the functionality of an electricalconnection between a battery and the powered impeller unit.
 5. Therespirator of claim 1, wherein the respirator comprises an externalmoisture barrier.
 6. The respirator of claim 1, wherein mechanicalactivation or electrical malfunction triggers formation of a seal toclose the engineered gap between the edge of the face mask and the faceof the wearer.
 7. The respirator of claim 6, wherein the seal is formedbetween the face of the wearer and at least one strip of flexiblematerial on at least one edge of the mask.
 8. The respirator of claim 1,wherein the face mask includes a molded interior surface that allows aflow of air directed within an internal cavity of the face mask toradiate out in an arc substantially parallel to the interior surface ofthe face mask to peripheral edges of the face mask to prevent a lateralmixing of external unpurified air into the interior of the face maskfrom the engineered gap between the edge of the face mask and the faceof the wearer.
 9. A respirator comprising: a face mask shaped to coverthe mouth and nose of a wearer and to avoid covering an eye region ofthe wearer when worn by the wearer; a strip of flexible material alongan outer edge of the face mask that contacts the face of the wearer whenworn by the wearer; at least one air filter attached to the face maskand configured to filter unpurified air to provide breathable air; and apowered impeller unit mounted on the face mask, the impeller unit beingoriented to emit the breathable air inside the face mask in asubstantially 360 degree plane.
 10. The respirator of claim 9, whereinthe face mask is configured to form an engineered gap between the outeredge of the face mask and the face of the wearer when worn by thewearer, wherein the engineered gap is configured to allow a positiveflow of the breathable air together with exhaled air to exit the facemask and exclude ingress of external unpurified air.
 11. The respiratorof claim 9, further comprising a releasable attachment point on the facemask adapted for releasably coupling the face mask to the face of thewearer via eyewear or head gear worn by the wearer.
 12. The respiratorof claim 11, wherein the releasable attachment point comprises at leastone magnet positioned on the face mask.
 13. The respirator of claim 12,wherein the at least one magnet is configured to provide a snap fitbetween the face mask and a corresponding magnetic strip on the eyewearor head gear to secure the face mask to the face of the wearer.
 14. Therespirator of claim 12, wherein the magnet provides the functionality ofan electrical connection between a battery and the powered impellerunit.
 15. A respirator comprising: a face mask shaped to cover the mouthand nose of a wearer and to avoid covering an eye region of the wearerwhen worn by the wearer, the face mask comprising a curved interiorsurface defining a cavity between the face mask and the face of thewearer; a strip of flexible material along an outer edge of the facemask that contacts the face of the wearer when worn by the wearer; atleast two substantially opposing air supply lines in fluid communicationwith the face mask, wherein the curved interior surface of the face maskdefines a path between the at least two opposing air supply lines forpositive streams of laminar flow of air; and an air filter forfiltration of the laminar flow of air, wherein the at least two opposingair supply lines are spaced apart and directed to allow the streams ofthe laminar flow of filtered air to collide at an intersection regionwithin the cavity of the face mask creating a turbulent flow of air thatradiates away from the intersection region therein for supplyingfiltered breathing air to the wearer and exclusion of outside unpurifiedair.
 16. The respirator of claim 15, wherein the face mask does not forma seal around the face region of the wearer, wherein the face mask isshaped to avoid covering an eye region of the wearer when attached tothe face region.
 17. The respirator of claim 15, wherein the face maskinterior surface is molded to allow the turbulent flow of air within thecavity of the face mask to radiate out thereby preventing a venturieffect entraining outside air and providing a control of bleed air to anexterior of the face mask.
 18. The respirator of claim 15, wherein therespirator comprises an external moisture barrier.
 19. The respirator asclaimed in claim 15, wherein mechanical activation or electricalmalfunction triggers formation of a seal between the edge of the facemask and the face of the wearer.
 20. The respirator of claim 19, whereinthe seal is formed between the face of the wearer and the strip offlexible material.